DURING the past year there has been in the United States a large increase in the use of fermented milk in the treatment of disorders of digestion and nutrition. A clearly discernible influence in bringing about this increase lies in the publications made by Professor Metclmikoff and his colleagues in reference to the fermented milk known as lacto-bacilline. The statements made by these scientific workers have been repeatedly exaggerated by persons having a commercial interest in the sale of certain kinds of fermented milks. It is apparently true that many physicians have been influenced by these statements in the direction of recommending among their patients a much wider use of fermented milk, and especially of lacto-bacilline, than was previously the case. Moreover many persons have decided without the advice of a physician to make a trial of some form of fermented milk or of some form of lactic acid ferment capable of acting upon milk sugar. It appears that this dietetic practise is still on the increase and likely to modify the habits of a not unimportant part of the community in respect to diet. In view of this fact it seems to me desirable to consider from a critical standpoint the therapeutic effects supposed to be derivable from the use of fermented milks, and more especially from milk that has been fermented through the use of the B. bulgaricus recommended by Professor Metchnikoff and now widely employed in the.production of lacto-bacilline. I believe that at the present time there exists a considerable confusion of mind as to what may or may not reasonably be expected in the way of therapeutic results from the use of milk which has undergone lactic acid fermentation. It is the object of this paper to consider briefly the elements which should enter into the formation of a judgment as to the therapeutic efficacy of lacto-bacilline and allied milk products.

In order to be able to form an unimpeachable judgment on the therapeutic action of a fermented milk, it is necessary that experiments of a very painstaking sort should be carried on in a number of individuals for considerable periods of time. Experiments of a kind calculated to furnish a firm scientific foundation for a rational use of fermented milks have not yet been made. Such experiments in order